DE2420001A1 - STORAGE TARGET FOR A CATHODE BEAM TUBE AND THE PROCESS FOR MANUFACTURING IT - Google Patents

Description

D-IPL-ING. KLAUS NEUBECKER

Patent attorney
4 Düsseldorf 1 ■ Schadowplatz 9

Düsseldorf, April 24, 1974

PF 2050
7439

Tektronix, Inc.

Beaverton, Oregon, W St. A.

Storage target for a cathode ray tube
and method of making it

The present invention relates to cathode ray tubes,. in particular cathode ray tubes with improved storage behavior, storage targets therefor and a method for production such storage targets.

US Pat. No. 3,531,675 describes a cathode ray storage tube in which the storage target is provided with elevations which have been etched out of the insulating substrate. the
Elevations and the area from which the elevations protrude,
are coated with a thin layer of transparent conductive metal oxide to form a collector electrode. on
this collector electrode is placed in a dielectric layer,
and the remaining areas of the elevations protrude outward beyond the dielectric layer. Such a memory target can only be manufactured at high cost because of the etching of the substrate for the purpose of forming the bumps, and the subsequent formation of the

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Telephone (O211) 32O8 58

Telegrams Custopat

dielectric layer can occur as a result of fluctuations Etching lead to different thicknesses at different points on the target. The area of the elevations also fluctuates as a result Non-uniformities of the substrate and its manufacture. The etched structure of the substrate makes it difficult to remove irregularities and detect defects in the elevations and the dielectric position. The work areas of the surveys can thereby are adversely affected that phosphor adheres too far to the bumps, so that the collection efficiency is reduced.

The present invention is directed to a cathode ray tube, which is provided with a storage target. The memory target has a dielectric support body on which a conductive Location is applied. Points or elevations, metallic particles with a substantially conical or continuous course are connected with their bases to the conductive layer, while their vertices or tips protrude beyond the top of the dielectric storage layer, so that collector areas for the Trapping secondary emitted electrons are formed by the dielectric.

Such a storage target leads to better collection effectiveness, because the fluorescent surface surrounding or adjacent to the collector points or elevations is controlled in this way, that the collector points or elevations result in a larger collector surface. This enables information to be transferred to the storage target to write faster using the electron beam and a

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get greater luminance. The lifetime of this storage target is longer because it is possible to work with a lower potential after the target wear is lower at lower work potentials. The memory target according to the present invention can be manufactured more easily and is therefore more economical. It can be regenerated because the collector points or elevations have been removed and the support body with the one on it conductive layer can be used again to make a new target. The manufacture of the memory target according to the present invention The invention can be monitored more effectively, which leads to better yields.

In accordance with procedural aspects of the present invention, a memory target is advantageously manufactured, by placing a layer of photopolymerizable material, in which a dispersion of conductive particles is contained, on a conductive one Layer is applied to a support body. The layer of photopolymerizable material is exposed to light through a mask applied, which has the desired division or grid for the collector elements, so that the photopolymerizable material polymerized in the areas activated by the light. The photopolymerizable material is washed out so that the Remaining collector elements made of conductive particles with a certain pattern. A layer of photopolymerizable, fluorescent particles containing material is applied to the conductive layer and the collector grid, whereupon through the collector grid Light is supplied what the photopolymerizable material

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polymerize in the areas activated by the light. This layer of photopolymerizable material is washed out, so that the unactivated photopolymerizable material is removed from around the collector elements and the dielectric Phosphor particles forming the storage layer remain, with the vertices or tips of the collector elements protrude beyond the outer surface of the dielectric storage layer.

According to the invention, a cathode ray tube with a storage target is intended be produced, which is provided with a continuous conductive layer to which a collector grid or a collector matrix of conductive particles, and on the continuous conductive layer is a dielectric memory target applied with the outer portions of the conductive collector elements over the outer surface of the dielectric memory target layer protrude.

The storage target according to the invention has an improved possibility in order to collect secondary electrons, since a larger area is available to the collection means and thus the collection effectiveness is increased. A cathode ray tube equipped with a storage target according to the invention can with higher Write speed and has increased luminance. In addition, the cathode ray tube according to the invention is longer Lifetime because it can be operated at a lower potential at which target wear is slower. Further the storage target according to the invention can be easier and more economical

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be produced more economically, because its production can be kept better under control, which leads to a lower proportion of Committee leads. In addition, the support body with the conductive layer arranged thereon can be regenerated since the collector elements are easily removable. The collector matrix produced on the conductive layer of the support body can be an integral Photomask can be used when the dielectric memory target will be produced.

The invention is explained below close to exemplary embodiments in conjunction with the accompanying drawings. In the Drawing show:

1 schematically shows the side view, partly in section, of a cathode ray storage tube according to the invention;

Fig. 2 is a cross-sectional view to illustrate the manufacture the matrix with the conductive points on the conductive layer of a support body;

Fig. 3 is a cross-sectional view of the conductive points on the conductive layer of the support body;

Fig. 4 is a cross-sectional view showing the fabrication of the dielectric memory target;

Fig. 5, partly broken away and partly in cross-section, is a perspective view of the completed

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Memory target structure; ·

6 shows, on an enlarged scale, a cross-section through part of the memory target of FIG. 5;

Fig. 7a i »in perspective in a partially broken away representation and 7b

development views of further options for implementing the storage target; and

8 is a perspective view of a corner region of a front plate of a curved front side of a cathode ray tube with a large viewing area.

In detail, FIG. 1 shows a cathode ray storage tube 10 with a piston 12 made of insulating material, inside it an electron gun system with a heating coil 14, a cathode 16 to be connected to a high negative potential, a control grid 18 and a focusing and acceleration structure 20 is arranged. One through the electron gun system generated electron beam 22 with high velocity electrons is deflected in the horizontal direction by horizontal baffles 24 and deflected in the vertical direction by vertical baffles in accordance with an input signal which is a Input terminal 28 applied and fed through this a conventional deflection circuit 30, which with the horizontal and vertical Deflector plates are connected so that the electron beam is selectively along the storage target in accordance with the input signal 32 at the end of the piston 12 opposite the electron beam

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generating system is positioned.

There are also one or more flood electron generation systems in the storage tube 34 with a cathode 36, a control grid and an anode 40 housed. The flood electron generation systems 34 are on the inside of the piston 12 next to the output side Ends of the vertical baffles 26 supported. The cathodes 36 are conventionally operated at a low Voltage level, typically ground, operated while the control grid 38 is connected to a low negative potential are. Electrical 'emitted by the flood electron generation system 34 Low velocity waves diverge into a conical beam and are uniformly distributed across the storage target 32.

On the inner surface of the piston 12 are between the flood electron generator systems 34 and the storage target 32 arranged a plurality of electrodes. These electrodes are preferably as spaced from each other arranged coatings formed from conductive material, and the first corresponding coating 42 is used in primarily as a focusing electrode for the generation systems used by the flood electrons 34 emitted flood electrons. The first coating 42 is connected to a suitable positive potential. A second wall coating 44 acting as an electrode is arranged at a distance from the first coating 42 and is electrical connected to a positive potential to act as a focusing and collimation electrode. A third acting as an electrode Coating 46 is spaced from coating 44

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ordered and connected to a positive potential to likewise to act as a focusing and collimation electrode. As a result of the collimation effect of the ones attached to the walls Electrode coatings are the electrons from the tide electron generation systems 34 distributed uniformly over the area of the storage target 32.

Between the third coating 46 and the storage target 32 there is a fourth wall coating 48 in the form of an electrode Arranged at a distance from the third coating 46, which is connected to a positive potential. The fourth coating also serves as a focusing and collimation electrode for the flood electrons, as well as an auxiliary collector electrode around a Part of the secondary electrons emitted by the storage target 32 to catch.

The coatings 42, 44, 46 and 48 are at positive potentials decreasing size connected, with the highest positive potential to the electrode in view of an optimal mode of operation 42 is connected.

The storage target 32 has an insulating end plate 50 with a transparent target electrode 52 over which a row conductive points 54 in the form of a point grid and a dielectric layer 56 are brought. The insulating end plate 50 forms a support body and is made of a transparent material such as glass. The target electrode 52 is a thin transparent sheet

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layering, preferably of tin oxide, which is suitably applied to the midpoint of a voltage divider with resistors 58 and 60 is connected, which are connected between a positive potential and ground ■. The resistor 58 is variable and is set so that that the target electrode 52 is applied with the correct working voltage. Instead, the target electrode 52 can also be connected to an amplifier device in order to read out information stored on the storage target electrically.

The points 54 are conductive particles, preferably made of cobalt, and have a preferably substantially conical structure, with their bases connected to the electrode 52, while their apex or point-outward from the outer surface of the dielectric Position 56 protrude from. The points 54 form collector electrodes, which are explained in more detail below and the points can also have a shape other than a conical shape, for example pyramidal, triangular, etc. be. The dielectric layer 56 is phosphor, preferably P-1 phosphor.

Information is transferred to the storage target 32 by means of the electron beam 22 written, what happened in the form of a signal curve. hen that acts on the vertical baffles while the beam is deflected in the horizontal direction by means of the horizontal deflection plates 24. In addition to the electrical reading the information written on the storage target is visible through the transparent end plate acting as a carrier element 50 reproduced. In operation, the tube potentials

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adjusted so that the beam 22 has a relatively high writing speed and can generate secondary electrons when it strikes the dielectric layer 56. That from the electron beam 22 acted upon area is at the potential of the points 54 (collector electrodes) and the target electrode 52 of ground level raised off so that the dielectric target glows there (phosphorescent). These secondary electrons are then through the points 54 (collector electrodes) collected, and the areas of the storage electric impinged on by the electron beam 22 are positively charged, so that flood electrons from the flood electron generation systems 34 are attracted to these positively charged areas. They emit secondary electrons in proportion One of them, whereby the secondary electrons are collected via collector points 54, which form the positively charged (described) Areas of the dielectric storage layer 56 are adjacent so that the information can be visually observed and used for purposes of study or photography can be preserved indefinitely. The target can thereby be erased in a conventional manner be that the target electrode receives a pulse that the storage dielectric to the potential of the collector electrodes (Points 54) and then lets it sink to the ground level, so that the tide electrons hold it there until the electron beam 22 writes information on it again. For more information on how the bistable memory targets work of this type, reference is made to the aforementioned US Pat. No. 3,531,675.

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The production of the memory target will now be described with reference to FIGS. 2-6 32 explained. As shown in Fig. 2, a transparent body 62 has a photo mask 64 with one disposed therein Hole matrix. The transparent end plate 50 with Ser transparent conductive target electrode 52 is placed on the photomask 64. A frame 66 is placed around the perimeter of the end plate 50 arranged, and a photopolymerizable slurry 68 made of polyvinyl alcohol, Water, ammonium dichromate, cobalt powder (2 - 5, u) and isopropyl alcohol is applied to the conductive, target electrode 52 poured forming layer.

Any other conductive particles or particles that are made conductive other than cobalt can be used, but for Following the background contrast, darker particles with reduced reflection behavior are more favorable. Cobalt is black and leads to optimal working properties. The particles can also be made of the same material as the conductive layer.

A collimated light source 70 is used to emit light beams 72 through the transparent body 62, the holes in the photomask 64, the end plate 50 and the target electrode 52 forming a conductive layer in the slurry 68 so that the slurry 68 is activated by light and the polyvinyl alcohol in them Areas polymerized.

The frame 66 is removed and the target assembly is filled with water washed so that the unactivated pulp is removed and a grid with cobalt dots remains.

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A shrinking agent such as acetone, aqueous, is added to the target structure Ammonium sulfate, alcohols or other hydrophilic substances are supplied so that the cobalt particles shrink through the rapid extraction of H ^ O and the cobalt dots 54 arise, which form a pronounced luminous dot matrix on the conductive layer forming the target electrode 52 as shown in FIGS. 3 and 5. The target structure is then dried.

A photopolymerizable slurry 74 made from polyvinyl alcohol, water, Dimethyl sulfoxide, ammonium dichromate and phosphor is applied to the target electrode forming conductive layer 52 and the dots 54, as shown in FIG. The collimated light source 70 then sends through the end plate 50 and the target electrode 52 forming conductive layer in the slurry 74 light rays 72 that activate the slurry 74 in the areas where none Points are arranged so that the polyvinyl alcohol polymerizes in these areas.

As you can see, no photo mask is required for this process, because the conductive points form an integral photomask, so that no polymerization of the in the area of each conductive point Polyvinyl alcohol takes place.

The build-up is washed out with water that does not activate the Slurry removed, leaving a layer of light activated slurry which forms a dielectric layer. This target structure is then softened by the shrink agent causing shrinkage

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of the conductive particles of the dots is inserted, and this shrinking process makes the dielectric layer denser Shrink structure so that the dielectric surrounding the individual points shrinks away from the points and thus one exposes a large area of the individual points. Although it was assumed that the photopolymerizable material for the formation of the matrix of conductive collector segments and the dielectric layer is in the form of a slurry, but this may Material can also be designed as a photopolymerizable dry film. As can be seen from FIGS. 5 and 6, the area increases of the dielectric memory layer 56 surrounding the individual points 54 in an upward direction away from the points, so that a annular surface 76 is formed around it, which can best be referred to as a funnel-shaped opening. This results in the increased collector area created by each collector point 54 is provided to collect the secondary electrons more effectively. The points also extend roughly with a quarter of its height above the outer surface of the dielectric Memory location 56.

After the storage target structure has shrunk, it becomes at baked at a suitable temperature in an oven to remove organic binders and the dielectric storage layer leave behind which contains essentially phosphor material. The storage target is then completed and affixed to the piston 12 in a conventional manner by frit sealing methods, whereby the end plate 50 forms the front side »

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The dot matrix with the dots 54, which the collector electrode structure forms, is preferably designed so that the center distance between adjacent points is less than the diameter of the electron beam 22, so that an improved collector device for collecting secondary electrons, an optimal one Resolution of the target, elimination of trace shadowing and improved visual reproduction, as well as reading accuracy of the information stored on the bistable memory target can be obtained. The collection effectiveness against Secondary electrons through the collector points will be through the increased surface area and control of the fluorescent surface surrounding the points. This leads to a higher writing speed and an improved luminance of the target. The service life of the storage target is increased because the target is at works at a lower work potential after the wear and tear of a target occurs more slowly at lower work potentials.

Fig. 7a shows an embodiment of the memory target in which the Collector segments 54a of particulate conductive material continuous, are approximately wedge-shaped elevations, the base areas of which are connected to the conductive layer 52a and their vertices protrude beyond the outside of the dielectric layer 56a. Thus, alternate rows delimit the dielectric Position and the conductive collector segments the target structure of Fig. 7a. The collector segments built up in the form of particles 54b can also be discontinuous, as shown in FIG. 7b, and the dielectric layer 56b is in FIG

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the areas where the collector segments are not continuous are.

The areas of the dielectric layer 56a and 56b in the vicinity of the collector segments 54a and 54b are inclined to to obtain a larger collector area in the same way as with respect to the collector-point matrix of FIGS. 2-6.

The construction of the targets according to FIGS. 7a and 7b is produced in the same way as that explained in connection with FIGS. 2-6 and the collector segments with the conductive particles can take any shape desired to achieve the desired result.

The embodiments explained above are on a plane Support body directed on which the thin layer of conductive material is located and on which the collector points or conductive particles forming collector segments are connected to a conductive layer. A layer of dielectric Memory material covers the conductive layer, the dielectric layer adjacent to the points or segments being inclined or beveled surfaces, while the vertices of the points or segments over the top or the outside of the dielectric layer protrude, so that a memory target with planar structure is obtained.

In the embodiment of FIG. 8, a front plate 78 made of glass has curved inner and outer surfaces, the inner surface

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with a conductive coating 52c, conductive collector points 54c and a dielectric layer 56c, which is in the in the same way as previously described. The faceplate 78 includes an integral wall 80 on which the tubular piston a larger cathode ray tube can be attached. The embodiment according to FIG. 8 thus relates to a curved one Storage target that works in conjunction with cathode ray storage tubes can be used that have a larger observation area.

The memory target of the present invention is easier to manufacture and therefore more economical. The support body with the conductive layer located thereon can be regenerated, since the matrix with the dielectric layer and / or the conductive collector elements can be removed, so that the support body with the conductive layer located thereon again can be used in connection with the production of a new memory target. The manufacture of the memory targets according to the present invention Invention can be monitored better, so that better production figures can be achieved.

The invention thus provides a cathode ray storage tube with a storage target that has a plurality of segments of the collector electrode which protrude through the dielectric layer of the storage target. These segments contain points or continuous or interrupted surveys from conductive

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2A20001

Particles that are photocopied onto the collector electrode have been applied. Then the dielectric storage layer is put over it, which has the right thickness, so that the segments protrude beyond the dielectric and thus collector surfaces are obtained, which the secondary emitted Catch electrons from the dielectric.

Claims ;

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Claims (27)

P a t e η t a η s ρ r ü c h e: Storage target for a cathode ray tube, with an insulating Support body, characterized in that one surface of the support body has a conductive coating is provided, over which a dielectric storage layer is arranged, and that a matrix of particulate conductive material composed of elements with ends connected to the conductive coating, extending through the dielectric storage layer and extend with free ends over an outer surface of the dielectric storage layer protrude outwards. 2. Storage target according to claim 1, characterized in that the surface is flat. 3. Storage target according to claim 1, characterized in that the surface is curved. 4. Storage target according to one of claims 1-3, characterized in that that the insulating support body is transparent. 5. Storage target according to one of claims 1-4, characterized in that that the conductive coating is transparent. 6. Storage target according to one of claims 1-5, characterized in that that the matrix of conductive elements has points with a substantially conical shape. 409845/0876 7. Storage target according to one of claims 1-6, characterized in that that areas of the dielectric storage layer in the vicinity of the conductive elements beveled surfaces to have. 8. Storage target according to claim 1, characterized in that the matrix of conductive elements contains continuous segments. 9. Storage target according to claim 1, characterized in that the conductive element matrix contains discontinuous segments. 10. Storage target according to claim 8 or 9, characterized in that that the segments are wedge-shaped. 11. Storage target for a cathode ray tube with an insulating Support body, characterized in that one surface of the support body has a conductive coating is provided, over which a dielectric storage layer is arranged, that a matrix having inclined faces Openings is provided in the dielectric storage layer and conductive elevations are integral in the openings with the conductive coating having their outer ends outwardly over an outer surface of the dielectric storage layer protrude. 409845/0876 12. Storage target according to claim 11, characterized in that the conductive bumps are essentially conical in shape and the beveled surfaces are adjacent to the conductive bumps are. 13. Storage target according to claim 12, characterized in that the bases of the conically shaped elevations are connected to the conductive coating and vertices of the elevations extend outwardly beyond the outer surface. 14. Storage target according to claim 11, characterized in that the conductive bumps include conductive particles that form substantially conically shaped points. 15. Storage target according to claim 11, characterized in that the conductive bumps are wedge-shaped continuous segments. 16. Storage target according to claim 11, characterized in that the conductive bumps are wedge-shaped discontinuous segments. 17. Cathode ray tube with a faceplate on its inner surface there is a conductive coating, characterized in that a dielectric Layer with a matrix of beveled or tapered openings is arranged that in the beveled conductive segments are arranged or tapered openings, 409845/0876 which are connected with inner ends to the conductive coating and with outer ends from an outer surface of the dielectric layer protrude outward, wherein the conductive segments form a collector electrode that a Means are provided to direct a high speed electron beam onto the dielectric sheet and thereby to generate a charge grid in this, and that a device is provided for electrons of low speed towards the dielectric layer, the low velocity electrons from the charge grid attracted and secondary electrons are thereby emitted and captured by the collector electrode. 18. Cathode ray tube according to claim 17, characterized in that that the matrix of beveled or tapered openings is annular Contains holes. ' 19. Cathode ray tube according to claim 17, characterized in that that the matrix of tapered openings contains channels. 20. Cathode ray tube according to claim 19, characterized in that the channels are continuous. 21. Cathode ray tube according to claim 19, characterized in that that the channels are discontinuous. 22. Cathode ray tube according to claim 17, characterized in that 409845/0876 that the conductive segments comprise particles of conductive material. 23. Cathode ray tube according to claim 17, characterized in that that the front panel is flat. 24. Cathode ray tube according to claim 17, characterized in that the front plate is curved. 25. A method for producing a storage target suitable for a cathode ray tube according to any one of claims 1-24, characterized in that a layer of photopolymerizable material with a dispersion distributed throughout it conductive particles applied to a conductive coating of a dielectric support body. Light that the polymerizable Material activated with polymerisation of the same in areas struck by the light, through an aperture matrix passed in a photomask, the photopolymerizable material with removal of the unpolymerized Material and leaving segments of conductive particles washed out, a layer of photopolymerizable material with phosphor particles dispersed therein applied to the conductive coating and the segments of conductive particles, Light that causes the photopolymerizable material to polymerize in the areas except where the segments are, activated, introduced into the photopolymerizable material; and the photopolymerizable A09845 / 0876 Material with removal of the unpolymerized material is washed out leaving phosphor layers. 26. The method according to claim 25, characterized in that the segments of conductive particles are treated with a shrink agent be exposed to more densify the conductive particles. 27. The method according to claim 25, characterized in that the fluorescent layer of the treatment with a shrink agent is set to allow the layer to shrink away from the segments, exposing a larger area of the segments. KN / sg5 409845/0876 ft Blank page